The present invention generally relates to air traffic control, and, more particularly to a method and apparatus for determining if clearance has been complied with.
A clear understanding between pilot and controller of the assigned clearance is essential for safe and efficient operations. Since the inception of radio communication, the aviation community has taken several steps to limit the possibility for misunderstandings by the use of standard operating procedures and phraseology wherever possible. Even so, there have been incidents where the flight crew""s failure to comply with an air traffic control clearance has occurred. Monitoring aircraft parameters to ensure adherence to ATC instructions is one of the flight crew""s primary responsibilities. Many crews write down ATC clearances on paper to help them remember. As an aid to the pilot, in the early 60s, several aircraft manufacturers added an altitude alerting function. The function alerts the flight crew if the aircraft""s actual altitude deviates from the altitude set by the pilot. Even though this system only monitors one parameter and is manually set, the system has proven itself useful in helping to reduce altitude clearance violations.
Data link technology is now being used between flight crews and controllers to exchange messages to request and respond to clearances, and to send ATC-requested reports. This form of communication is expected to increase in the future as airspace becomes more crowded. In addition to clearance communication, ATC is also using data link technology for surveillance enabling easier detection of clearance violations outside of radar coverage. Although a relatively small number of aircraft use data link technology today, in the future, almost all aircraft will use some form of data link for ATC communication. However, as airspace congestion increases, strict adherence to ATC clearances will become even more essential if current safety standards are to be maintained.
Data link technology as described hereinafter can be used as an enabler to develop a new and comprehensive monitor function that can reduce crew workload and reduce airline operating costs by reducing the number of clearance violations. The present system stores data linked clearance information and monitors aircraft performance with respect to the assigned clearance alerting flight crews to a clearance violation. In some cases in the present system the flight crew can be alerted prior to a potential violation. In other cases the flight crew will be alerted as soon as the violation occurs. The hereinafter described system according to the present invention comprises a Compliance Monitor and Pilot Alerting Sub-System (COMPASS).
A prerequisite of the present COMPASS system is the capability to communicate with ATC via data link communication. Currently there are two protocol standards for ATC data link communication and there may be others in the future. The basic operating concept behind the COMPASS system centers on the use of ATC clearance information contained in ATC data link messages combined with COMPASS monitoring logic; it is thus protocol independent. To accommodate a wide range of avionic architectures, COMPASS can be implemented as a software function, or as a separate LRU that receives clearance information from other data link systems.
ATC clearance data is automatically entered into the system from uplink clearances accepted by the flight crew. The system monitors aircraft parameters to determine if the clearance is being complied with as pilots do manually. If the system determines the aircraft is about to violate, or is in violation of an ATC clearance or report request, the system alerts the pilot.